Realization of photo-electrochemical water splitting to generate H2 alternative fuel requires the facilitation of the kinetically-sluggish oxygen evolution reaction (OER) occurring at the photoanode. To do so, there is a need to develop new methods to assemble suitable OER co-catalysts at the semiconductor-solution interface. Although Metal-Organic Frameworks (MOFs) are frequently used as precursor materials to synthesize high surface area, effective OER electrocatalysts, until now their utilization as co-catalysts in a working photo-electrochemical cell (PEC) has remained underexplored. As a proof-of-concept, here we provide a simple route for modification of BiVO4-based photoanodes with highly-active porous cobalt-oxide co-catalysts, converted from a cobalt-imidazolium MOF (ZIF-67). Photo-electrochemical and impedance spectroscopy analysis reveal that the co-catalyst significantly accelerates photoanodic OER (rather than serving as a surface passivation layer), and thus greatly improves the overall PEC performance. Hence, given the chemical flexibility of MOFs, this work provides a new tool-kit for designing efficient water splitting PECs.
Bibliographical noteFunding Information:
S. G. thanks the support of the Spanish Ministerio de Ciencia, Innovación y Universidades through the project ENE2017-85087-C3-1-R. I. H. thank the support of the Israel Science Foundation (ISF) (Grant No. 306/18), and the Ilse Katz Institute for Nanoscale Science and Technology for the technical support in material characterization.
© The Royal Society of Chemistry 2019.